The Axis-Ratio Distribution of Galaxy Clusters in the SDSS-C4 Catalog as a New Cosmological Probe

Abstract

We analyze the C4 catalog of galaxy clusters from the Sloan Digital Sky Survey (SDSS) to investigate the axis-ratio distribution of the projected two dimensional cluster profiles. We consider only those objects in the catalog whose virial mass is close to 10^{14}h^{-1}M_{sun}, with member galaxies within the scale radius 1000 kpc. The total number of such objects turns out to be 336. We also derive a theoretical distribution by incorporating the effect of projection onto the sky into the analytic formalism proposed recently by Lee, Jing, & Suto. The theoretical distribution of the cluster axis-ratios is shown to depend on the amplitude of the linear power spectrum (sigma_8) as well as the density parameter (Omega_{m}). Finally, fitting the observational data to the analytic distribution with Omega_{m} and sigma_{8} as two adjustable free parameters, we find the best-fitting value of sigma_{8}=(1.01 +/- 0.09)(Omega_{m}/0.6)^{(0.07 +/- 0.02) +0.1 Omega_{m}}$. It is a new sigma_{8}-Omega_{m} relation, different from the previous one derived from the local abundance of X-ray clusters. We expect that the axis-ratio distribution of galaxy clusters, if combined with the local abundance of clusters, may put simultaneous constraints on sigma_{8} and Omega_{m}.

accepted for publication in ApJ, 17 pages, 3 figures, improved analysis, more discussion on the validity and the caveats of the model

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Cited by in corpus (8)

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• Spherically Averaging Ellipsoidal Galaxy Clusters in X-Ray and Sunyaev-Zel'dovich Studies: I. Analytical Relations
• Dark Sector Coupling Bends the Superclusters
• Automatic Machine Learning Framework to Study Morphological Parameters of AGN Host Galaxies within $z<1.4$ in the Hyper Supreme-Cam Wide Survey
• Evolution of axis ratios from phase space dynamics of triaxial collapse